1. Field of the Invention
The present invention relates to heat exchangers and in particular, to modular heat exchangers used with internal combustion engines in vehicles or industry.
2. Description of Related Art
Engine cooling radiators used with internal combustion engines in trucks or industry are often quite large. Those used with stationary diesel-electric generator sets in particular can have cores with an overall size of from six to eight ft. (1.8 to 2.4 m) on a side or even larger. Such radiators have usually been made with multiple cores because a single core of such size is difficult to manufacture. Industrial radiators such as these are typically of cooper/brass soldered construction, wherein solder-coated brass tubes are pushed through holes in a stack of copper fins, which have been held in the desired spacing in a grooved book jig, to form a core block. The core block is then baked in an oven to solder the tubes to the fins. Following this, the tube ends are inserted into brass headers at each end of the core block and soldered, to form a core. The height of such a core is limited by the ability to push long, thin tubes through the holes in the fins, with 48 in. (1.22 m) being close to a practical maximum. Similarly, the size of a typical book jig limits core widths to about 48 in. (1.22 m).
Therefore, to make a 72 in. (1.83 m) high core assembly, as the example, two 36 in. (91 cm) high cores are joined by bolting header-to-header, with a connecting frame and gaskets in between. Such a core assembly would be 72 in. (1.83 m) high (plus the thickness of the frame) and up to 48 in. (1.22 m) wide. It would have an inlet header at the top and an outlet header at the bottom to connect to inlet and outlet tanks.
To make a 72-in. (1.83 m) wide core assembly, two 36 in. (91 cm) wide core blocks are solder connected side-by-side to a single common inlet header at the top and a single common outlet header at the bottom. Usually a core separator strip is placed between the cores, primarily for appearance and to block any bypass cooling air between the cores. Such a core would be 72 in. (1.83 m) wide and up to 48 in. (1.22 m) high.
For a core assembly of overall size of 72 in. (1.83 m) by 72 in. (1.83 m), as shown in FIG. 1, two copper/brass core blocks 8′ are solder connected side-by-side to a single common header 78 at the top and bottom of the core blocks 8′ to produce a first core assembly. A second core assembly is constructed with two additional core blocks 8″ and two additional headers 78. The 36-in. (91 cm) high, 72 in. (1.83 m) wide core assemblies are then joined to a connecting filler frame 15 by bolting, with gaskets between the filler frame and each core header, the gaskets substantially the same as the gasket 75 between the radiator tank 100 and the top header 78 of upper cores 8′. The headers 78 of the core pairs are bolted, with gaskets 75, to a steel inlet tank 100 and outlet tank (not shown) with a core separator strip 77 between the side-by-side cores. Such a large core assembly of copper/brass material is expensive for two reasons. First, the price of copper and copper-based alloys is expensive and, second, the manufacturing method associated with soldered copper/brass radiator construction is labor-intensive.
Automobile and heavy truck radiators have long since abandoned costly copper/brass radiator construction in favor of CAB (controlled atmosphere brazing) aluminum core construction with plastic tanks. PTA (plastic tank aluminum) radiators have tabbed aluminum headers which are crimped to a plastic radiator tank with an elastomeric gasket between. This type of construction is more automated, requires far less labor, is more consistent, uses less costly material, and results in a product which is lighter, stronger and which has demonstrated improved durability compared to copper/brass. However, the available CAB furnaces limit core size to not larger than about 48 inches square.
There is a need for a way to make large radiators for large vehicles and industrial applications using CAB aluminum cores.